Not just no, but hell, no! The whole assembly has no side to side stability. Looks like any sideways bump on either of the 19” ends, and it’s gone.
The whole assembly has no side to side stability.
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Totally agree.... If the unit is against a wall, I would have dealt with the side to side problem (the 30” direction) with a piece on the back that strengthens ‘the box’... could be corner pieces or even a piece that goes completely from one side to the other. You say the front was left open so that you could slide the tank in. How much clearance is there from the top of the tank to the underside of the board above? You mentioned that three sides have a 2.5 x 0.75” board running horizontally... you sure that you can’t run one on the 4th side as well... and perhaps run one horizontally down the middle between the front and the back? Those 2.5 x 0.75” boards aren’t quite the best at stiffening up the connection between the legs and the top but it should work well enough if the connection to the vertical legs is done right. Also, a board running horizontally down the center below the two ‘planks’ on the top would give them some support from below they don’t have right now. Since that board in the center would tie in to the horizontal members between the legs, that joint too would improve the lateral stability.
One thing I always do is try to run a test to see just how far things need to be taken before going nuts on increasing stiffness and stability. If you were to butt the legs up against something so that it didn’t move (and had someone hold the other two legs down so that they wouldn’t lift off the floor) and then put some sideways force against the top, does it feel too flimsy? How much sideways force gives you how much movement? If 200 lbs of force only move it a 1/16”, that’s on thing... however if only 25 lbs move it 3/4”, that’s totally different and a problem that needs to be addressed.
Yep…. I’m not impressed with the stability same as you. Needs bracing on all 4 sides. Gussets in the corners as well.
OP estimates that weight supported will be about 155 pounds. Heck, just have a 200+ pound butt sit on the table and see if it busts. Make sure the test butt does some serious wiggling to see if the thing collapses sideways.
Engineers do all sorts of calculations to size something to a certain strength plus a safety factor. For ultimate reliability though you apply a test load to verify the as constructed capability.